textproduct: Rapid City

This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.

KEY MESSAGES

- Unsettled and cool weather this weekend - Frost possible northeastern WY plains Sunday morning - Warming trend next week

DISCUSSION

(This Evening Through Friday) Issued at 142 PM MDT Fri Jun 12 2026

19z surface analysis had weak trough over the CWA with a frontal boundary across northern MT/ND. Water vapour loop had mean trough over central Canada with next shortwave trough of interest over southern AB/northwest MT, currently conjuring some shra/TS. Few CU over the CWA. Main concern this forecast is upstream shortwave trough.

Tonight/Saturday, shortwave trough slips east/southeast along frontal boundary. Nice band of 800-600mb frontogenesis sets up behind front tapping into limited moisture. Should see a band of showers over southeast MT/northeastern WY later tonight (probably poking into far western SD), peaking Saturday morning. Synoptic support quickly ends midday Saturday, allowing QPF band to dissipate. Gusty northwest winds expected on the SD plains Saturday given boundary layer flow/mixing. Temperatures tonight/Saturday near guidance.

Clearing skies and slackening wind Saturday night may lead to frost over northeastern WY plains Sunday morning. Will let later shifts take a look at potential headlines.

Looking ahead to next week, most guidance suggests slow expansion of upper/thermal ridge into the northern plains, but we'll still be under northwest flow aloft with potential for moisture-starved weak disturbances/fronts and even perhaps a smattering of PoPs. Overall general trend will be warmer/drier, however.

AVIATION

(For the 18Z TAFS Through 18Z Saturday) Issued At 1116 AM MDT Fri Jun 12 2026

VFR conditions will continue through this afternoon and evening. A system will push into NE WY late tonight, with rain showers developing after 13/08-10z along with MVFR/IFR ceilings. These showers and lowered flight conditions will be found across NE WY (including KGCC) and into the Black Hills, including KSPF and KCUT; transient LIFR conditions possible from 13/10-18z across these areas. Confidence is low that showers and lowered flight conditions will impact KRAP; have added a PROB30 group beginning at 13/12z for KRAP. Expect VFR conditions to persist outside of these areas across the western SD plains into central SD.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.

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